This invention relates to so called "curtain side" truck bodies and truck trailers for side loading and unloading, for example as described in U.S. Pat. No. 3,709,552.
In this type of trailer construction the side walls normally used as load carrying members are dispensed with so that the lading may be loaded and unloaded from the sides of the truck body.
A curtain is used to protect the lading from rain, and to some degree other environmental factors.
However, when certain heavy loads are carried, the load tends to cause the side rails and connecting transverse members to deflect in an arcuate concave pattern, which in turn applies a large floor load moment to the four vertical posts which support the top rails, and the roof.
In some cases this lading moment applied to the vertical posts has been sufficient to cause cracks or loose bolts in the area of the side rail and vertical post juncture.
In U.S. Pat. No. 4,595,231, rigid, semi-rigid, fully flexible, and pivotable joints are disclosed to overcome the problem of trucks and trailers having the rectangular frame subjected to deflection and longitudinal twisting in service under load. However, none of the joints described or illustrated in the Patent are directed to the problem of the lading load moment in the side rails applied to the vertical vertical posts in the front wall or the end wall of the truck or trailer.